rollup.config.build.js

import svelte from 'rollup-plugin-svelte';
import resolve from '@rollup/plugin-node-resolve';
import commonjs from '@rollup/plugin-commonjs';
import dsv from '@rollup/plugin-dsv';
import { terser } from 'rollup-plugin-terser'
import json from "@rollup/plugin-json";
import css from 'rollup-plugin-css-only';

export default [
	{
		input: 'src/main.js',
		output: {
			sourcemap: true,
			format: 'iife',
			name: 'app',
			file: 'dist/build/bundle.js'
		},
		plugins: [
			// Allow for importing csv files as modules
			dsv(),
			// And importing json files
			json(),

			svelte({
				compilerOptions: {
					dev: false, 
					hydratable: false
				}
			}),
			// we'll extract any component CSS out into
			// a separate file - better for performance
			css({ output: 'bundle.css' }),

			// If you have external dependencies installed from
			// npm, you'll most likely need these plugins. In
			// some cases you'll need additional configuration —
			// consult the documentation for details:
			// https://github.com/rollup/plugins/tree/master/packages/commonjs
			resolve({
				browser: true,
				dedupe: importee => importee === 'svelte' || importee.startsWith('svelte/')
			}),
			commonjs(),

			terser()

		],
		watch: {
			clearScreen: false
		}
	}
];